Usability and effectiveness of inhaled methoxyflurane for prehospital analgesia - a prospective, observational study.

BACKGROUND: Pain relief in the prehospital setting is often insufficient, as the administration of potent intravenous analgesic drugs is mostly reserved to physicians. In Australia, inhaled methoxyflurane has been in routine use by paramedics for decades, but experience in Central European countries is lacking. Thus, we aimed to assess whether user friendliness and effectiveness of inhaled methoxyflurane as sole analgesic match the specific capabilities of local ground and air-based EMS systems in Austria. METHODS: Observational study in adult trauma patients (e.g. dislocations, fracture or low back pain following minor trauma) with moderate to severe pain (numeric rating scale [NRS] ≥4). Included patients received a Penthrop® inhaler containing 3 mL of methoxyflurane (maximum use 30 min). When pain relief was considered insufficient (NRS reduction < 3 after 10 min), intravenous analgesics were administered by an emergency physician. The primary endpoint was effectiveness of methoxyflurane as sole analgesic for transport of patients. Secondary endpoints were user friendliness (EMS personell), time to pain relief, vital parameters, side effects, and satisfaction of patients. RESULTS: Median numeric pain rating was 8.0 (7.0-8.0) in 109 patients. Sufficient analgesia (reduction of NRS ≥3) was achieved by inhaled methoxyflurane alone in 67 patients (61%). The analgesic effect was progressively better with increasing age. Side effects were frequent (n = 58, 53%) but mild. User satisfaction was scored as very good when pain relief was sufficient, but fair in patients without benefit. Technical problems were observed in 16 cases (14.7%), mainly related to filling of the inhaler. In every fifth use, the fruity smell of methoxyflurane was experienced as unpleasant. No negative effects on vital signs were observed. CONCLUSION: In prehospital use, inhaled methoxyflurane as sole analgesic is effective for transport of trauma patients (62%) with moderate to severe pain. Older patients benefit especially from inhaled methoxyflurane. Side effects are mild and vital parameters unaffected. Thus, inhaled methoxyflurane could be a valuable device for non-physician EMS personnel rescue services also in the central Europe region.

[Volatile anesthetics for prehospital analgesia by paramedics-An overview]. / Volatile Anästhetika zur präklinischen Analgesie durch Rettungssanitäter ­ Eine Übersicht.

Treatment of acute pain is a central task in emergency medicine. Yet, prehospital pain relief is often insufficient or delayed since the administration of potent intravenous analgesic drugs (such as opioids) is mostly limited to physicians due to legal restrictions or training deficiencies in Germany and Austria. Frequently, prehospitally operating emergency physicians have to be demanded later for anguished patients limiting disposability of physicians for patients who are in a potentially life-threatening condition. Thus, inhaled analgesics could represent an interesting alternative.A mixture of 50% nitrous oxide and 50% oxygen (N2O, Livopan®) has been available in Germany and Austria for several years; however, prehospital use of Livopan has been merely realized and only one trial has been published. In addition, methoxyflurane (Penthrop®), a volatile anesthetic from the group of the dialkyl esters (2-dichloro-1:1-difluoroethyl-methyl-ester) was approved for the treatment of moderate to severe pain following trauma in adults in many European countries in recent years and was brought onto the market in Austria in 2018. Several in-hospital trials demonstrated high effectiveness in this setting.This article discusses the effects and prehospital areas of application of both substances in the light of the existing literature. We provide a narrative overview of the current study situation and report on a recently performed prehospital application study of methoxyflurane (Penthrop®) from Austria.The need for pressurized gas cylinders for the use of N2O represents a certain limitation in prehospital use. Furthermore, in certain injuries such as of the inner ear or a pneumothorax N2O should not be used and the risk of diffusion hypoxemia has to be addressed. Users should be particularly careful and limit the use in alcohol addicts and vegans. The advances of N2O are that it is odorless, has a fast onset of action, the usability in patients over 1 month old and has stabilizing effects on the circulation. Plenty of literature regarding prehospital as well as in-hospital use of nitrous oxide in emergency, obstetric and pediatric settings show its effectiveness as a single drug as well as in combination with other analgesics, such as paracetamol or various opioids. Its long tradition in Anglo-American countries is also based on its safety and low rate of side effects.Methoxyflurane is easier to store and handle and may be slightly more effective in severe pain after trauma; however, its approval is restricted to adults, where it works significantly better with increasing age, based on the declining minimal alveolar concentration (MAC) of all inhaled anesthetics with increasing age. Furthermore, decades of use of inhaled methoxyflurane in Australia have shown the drug is effective, safe and low in side effects and has a broad spectrum of applications. The use of methoxyflurane is limited in patients with severe hepatic or renal insufficiency and the characteristic odor has been described as unpleasant by some patients. In Europe, three large in-hospital trials showed strong pain relief in trauma patients, even comparable to opioids.Overall, based on the current evidence, the use of nitrous oxide and even more of methoxyflurane may be recommended also for prehospital use by skilled paramedics.

Comparing the McGrath Mac Video Laryngoscope and Direct Laryngoscopy for Prehospital Emergency Intubation in Air Rescue Patients: A Multicenter, Randomized, Controlled Trial.

OBJECTIVES: Tracheal intubation in prehospital emergency care is challenging. The McGrath Mac Video Laryngoscope (Medtronic, Minneapolis, MN) has been proven to be a reliable alternative for in-hospital airway management. This trial compared the McGrath Mac Video Laryngoscope and direct laryngoscopy for the prehospital setting. DESIGN: Multicenter, prospective, randomized, controlled equivalence trial. SETTING: Oesterreichischer Automobil- und Touring Club (OEAMTC) Helicopter Emergency Medical Service in Austria, 18-month study period. PATIENTS: Five-hundred fourteen adult emergency patients (≥ 18 yr old). INTERVENTIONS: Helicopter Emergency Medical Service physicians followed the institutional algorithm, comprising a maximum of two tracheal intubation attempts with each device, followed by supraglottic, then surgical airway access in case of tracheal intubation failure. No restrictions were given for tracheal intubation indication. MEASUREMENTS MAIN RESULTS: The Primary outcome was the rate of successful tracheal intubation; equivalence range was ± 6.5% of success rates. Secondary outcomes were the number of attempts to successful tracheal intubation, time to glottis passage and first end-tidal CO2 measurement, degree of glottis visualization, and number of problems. The success rate for the two devices was equivalent: direct laryngoscopy 98.5% (254/258), McGrath Mac Video Laryngoscope 98.1% (251/256) (difference, 0.4%; 99% CI, -2.58 to 3.39). There was no statistically significant difference with regard to tracheal intubation times, number of attempts or difficulty. The view to the glottis was significantly better, but the number of technical problems was increased with the McGrath Mac Video Laryngoscope. After a failed first tracheal intubation attempt, immediate switching of the device was significantly more successful than after the second attempt (90.5% vs 57.1%; p = 0.0003), regardless of the method. CONCLUSIONS: Both devices are equivalently well suited for use in prehospital emergency tracheal intubation of adult patients. Switching the device following a failed first tracheal intubation attempt was more successful than a second attempt with the same device.